Parametric Amplifier

A parametric amplifier is a low-noise amplifier used in satellite communications transponders to amplify very weak RF uplink signals. It operates by transferring energy from a high-frequency pump signal to the desired RF signal through a nonlinear reactive element, typically a varactor diode, enabling amplification with very low added noise.

Parametric amplifiers were historically used in satellite receivers where extremely low noise temperatures were required, particularly at higher frequency bands, but have largely been superseded in modern systems by solid-state LNAs based on GaAs or InP high-electron-mobility transistors due to their greater reliability, simplicity, and bandwidth.